The present invention relates to an electrophoretic display and a particle moving type display.
Conventionally, a display has been disclosed in, for example, a Japanese Laid-open Patent Application JP-A-2003-5225, in which colored charged particles are dispersed in an transparent medium, the particles are moved and thereby reflectivity is changed by means, which are disposed in a two-dimensional array, for controlling voltage to be applied to each pixel, and thus images are displayed.
In this display, a transparent medium containing colored charged particles dispersed therein is filled between a pair of substrates, voltage is varied that is applied between an electrode that is formed on a central part of a pixel of a lower substrate of the pair of substrates and an electrode that is formed in a stage part disposed on the lower substrate, and switching is carried out between a particle color and a background color for each pixel by the motion of the colored charged particles, thus images being displayed. When the colored charged particles are attracted onto the electrode that is formed in the stage part, the display exhibits a first color possessed by the colored charged particles. In addition, when the colored charged particles are moved onto the electrode that is formed in the stage, the display exhibits a second color possessed by the electrode formed in the stage part.
In such a display, when the colored charged particles are moved to the electrode formed on the stage part while the above first color (particle color) is exhibited, the electrode formed in the center of the pixel is exposed to produce different reflected light, thus causing a decrease in contrast ratio. To prevent this, a countermeasure may be taken such as coloring the electrode formed in the center of the pixel into the particle color. However, there arise problems such as deterioration in optical characteristics due to the difference in color as compared with the particle color, deterioration in electrical characteristics due to the colored layer, and an increase in cost. In addition, the above display is structured such that when changing images, particles are moved from the electrode formed in the stage part to the side opposite to the electrode formed in the center of the pixel. Therefore, the operation of changing the voltage of the electrode formed at the center of the pixel is weakened by the shield effect of the electrode itself that is formed in the stage part, and the particles that fail to move remain there. Thus, satisfactory reflectivity, contrast ratio, and response speed are not necessarily obtained.